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UNIVERSITY OF ILLINOIS 


Agricultural Experiment Station 


BULLETIN No. 217 


AN APPLE CANKER DUE TO 
CYTOSPORA 


By FRANK LINCOLN STEVENS 


URBANA, ILLINOIS, MAY, 1919 


CONTENTS OF BuuLerin No. 217 


PAGE 

DESCRIPTION OF THE CANKER...... eGiag tea ae OT ete SAO ecto 367 
are FOMGUG 86s G ak awe ee TO ER a caGee 368 
PROMALIONS occ © sic torets icles Sie, eid ese eee nee reyeencanete ete we ehstelacdisiishatelarCiate rahe etausveveia’ te 371 
PIMILAR /HUNGI ON ROSACEOUB “Ll WIGS <6 cisix.cic ied orstah ciate os ane oar ewe eae 372 
Valsas: On. Rose ceoun -FLORGS S15 s Giavarors sets eivie cpotasitan s Baloaiei ein abe ats aeerasaes 372 
SSIBLIOGRAP HY sows cies ois oie.0'.s Bsc ajewisles's sip lp Qiowinlste 5 sis ease lee On celetes Wal@tas 377 


AN APPLE CANKER DUE TO CYTOSPORA. 


By FRANK LINCOLN STEVENS, Proressor oF PLANT PATHOLOGY, 
UNIVERSITY OF ILLINOIS, IN COOPERATION WITH THE DEPART- 
MENT OF HORTICULTURE 


A canker on young apple trees which appears capable of doing 
much damage was submitted to the author for identification in the 
spring of 1918. Tho noted on only a few trees, its rapid and com- 
plete possession of the tree, together with the fact that it does not 
agree closely with other apple-tree cankers previously described, 
makes it worth while to give rather a complete statement of the 
present knowledge of it. 

The apple cankers were sent by Mr. G. P. Callender, of Altona, 
Illinois. He stated that he had received the trees from a certain nursery” 
company in New York, on April 27, 1918. Requests were made of 
the company that they send specimens of any cankers they might 
find in their orchards, but no reply was received. | 


DESCRIPTION OF THE CANKER 


One specimen was found on the main trunk of a young tree 
about 2 em. in diameter. The canker extended a total length of 
22 cm., completely encircling the tree thruout most of that distance, 
altho it extended 2 or 3 em. farther up and down on one side of the 
tree than on the other side. 

There was no abrasion or wound which seemed to mark the place 
of the original infection. Altho several lateral branches had been 
cut off from the portion found cankered, the wounds were in all 
eases nicely healing over with callous. The canker for the most 
part was of a tan color, similar to that which is frequently exhibited 
in young ecankers of apple blotch. Portions of the canker, toward 
one end, were of much darker bronzed or purplish color, altho at 
the other end of the canker this color was absent. 

The demarcation between the diseased and the healthy tissues 
was very sharp with a slight breaking away of the diseased from 
the healthy tissues. On removing the bark, a black transverse line 
about 1 mm. wide was disclosed, apparently separating the healthy 
from the diseased tissues. It is quite probable that the canker at 
this point was in dormant condition, resting, not progressive. The 
other end of the canker did not show sharp limitations between the 
diseased and the healthy tissues, which gradually faded, one into 
the other, and did not show externally the 2-em., dark, purplish band 
mentioned above, adjacent to this end of the canker. 


367 


368 BULLETIN No. 217 [May, 


The canker was studded thruout its area with black pustules 
having the appearance of pycnidia or perithecia. These were slightly 
raised conically above the surrounding surface, were black, about 
1 to 2 mm. in diameter, and were so abundant that an unbroken 
area of 5 square millimeters could scarcely be found. A color photo- 
graph of this twig was made June 5. 


THE FUNGUS 


The fungus is apparent to the eye, externally, as small black 
pustules under, or erumpent thru, the cuticle. On microscopic exam- 
ination these prove to be relatively large compound pyenidia made 
up of numerous irregularly arranged cavities in a mass of dense 
stromatie structure. Views of the pyenidia from various sections 
are shown in Figs. 1 to 11. 


Fic, 1—Cross-SECTION OF A PYCNIDIUM 


Fig. 1 shows a cross-section, i.e., a section in a plane parallel 
to the base of a pyenidium, which represents the condition most 
frequently found. There is a large number of locules, irregular in 
size and shape, but arranged in a circular manner around a sterile 
area, with their longer axes along the radii. Another pyenidium 
is shown in similar view in Fig. 2, and a section in the same diree- 
tion but farther from the base, in Fig. 3. Fig. 4 is drawn from a 
section longitudinal to the twig and parallel to the plane of the 
radius of the twig, therefore cutting from the top of the pyenidium 
to its base. The irregular locules are here shown, and the large 


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1919] AN APPLE CANKER DUE TO CYTOSPORA 369 


Figs. 2-11.—Cross AND VERTICAL SECTIONS THRU PYCNIDIA 


370 BULLETIN No, 217 [May, 


covering mass of sterile mycelium, all below the cuticle but break- 
ing thru it. 

Figs. 5 to 10 give similar views showing considerable variation 
as to the locules and their openings into the ostiole, but a general 
agreement in that the sporiferous cavities are covered-in all cases 
by a dense stromatie or clypeate structure. (Ectostroma, cf. Ruh- 
land.3?) Fig. 11 shows a similar section, but nearly tangential to 
the edge of a pycnidium. Fig. 12 shows the detail of the portion of 
the pyenidium marked ‘‘a’’ in Fig. 1. The interlocular material is 
seen to be a firm pseudoparenchyma, the walls of the outer cells 
being somewhat thicker than the walls of the inner cells. The en- 
tire inner surface of the locules is lined with a close palisade of 
conidiophores, which are in the main simple and narrow, and about 17 
to 20 » long by .5 to .7 » thick, tho in some instances they may 
branch, as figured by Aderhold.1° This conidiophore layer is shown 
still more clearly in Fig. 13. Fig. 14 shows the detail of the part 
marked ‘‘a’’ in Fig. 10. It is seen that in certain parts the fungus 
mycelium is loosely woven and with open interstices. Fig. 15 shows 
the spores, which are produced in very great number. They are 


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Fig. 12.—DETAIL OF PoRTION OF PYCNIDIUM MARKED ‘‘A’’ IN Fig. 1 | 


1919] AN APPLE CANKER DUE TO CYTOSPORA 371 


hyaline, 1-celled, obtuse, quite uniform in size (7x1.6 »), and either 
straight or slightly curved, 

The mycelium is thin and hyaline and by these two character- 
istics is easily distinguished from the mycelium of the black-rot 
fungus. Close search revealed no 
ascigerous structures. 


ISOLATIONS 


The fungus was easily secured in 
pure culture. Fragments from the 
interior of a pyenidium were 
placed in a drop of sterile water 
and portions of this drop then 
Fig. 13.—PorTION oF A CONIDIOPHORE transferred to tubes of melted 

rade’ corn-meal agar and poured into 
Petri dishes. Thousands of pure growths were thus secured. Corn- 
meal agar was also poured into Petri dishes and allowed to solidify. 
Then bits of diseased tissue from below the cortex were placed upon 
its surface. Invariably those bits gave rise to the same fungus se- 
eured by the dilution method. The fungus thus secured in pure 
culture was maintained for several months on various media. Tho 
the fungus vegetated luxuriantly on various agars it did not bear 
pycnidia in them, or spores of any kind. The colonies on all media 
were colorless and with a floccose, aerial mycelium. 

Inoculations from these pure cultures were made on apple and 
other twigs (pear, rose, 
blackberry, plum, and 
peach) in test tubes with 
a few cubic centimeters of 
water to keep the culture 
moist. These resulted in 
rapid growth and the de- 
velopment in the bark, in 
about three weeks, of very 
numerous pyenidia of com- 
pound, chambered struc- 
ture, identical with that 
found in the natural can- 
kers as described above, 
tho under these conditions 
there was always an exten- 


sive development of aerial 

mycelium not found under “7 

the less humid natural con- oo eS 

ditions. On:all é f Fig. 14—DETAIL OF PORTION OF PYCNIDIUM 
° n species 0 MarkKeEp ‘‘A’’ IN Fig. 10 


A; 
\EEAZ, 
S07) 71 


ut 


372 BULLETIN No. 217 [ May, 


twigs employed, except box-elder, cherry, and ‘maple, the fungus 
grew well, penetrating under the cortex thruout the whole length of 
the twig, some 8 to 10 em., and breaking out with its erumpent pyenidia 
over all as of the twig. On certain twigs, e.g., those of black- 
: berry, tho growth was abundant and rapid, the 
pycnidia were much smaller than on apple 
twigs, yet no difference was noticeable in the 
spores. Careful search was made in all cultures 
for an ascigerous stage, but none was found. 
No attempts to produce the disease on trees 
in the open were made because it was not thought 
wise to run any danger of giving it wider in- 
troduction in this state. From the laboratory 
evidence as well as from the statements of Mr. 
Callender it appears that this canker is one of 
very rapid development and one that might 
cause serious loss should it become widespread 
and suitable conditions for its development ob- 
tain. 


Fig. 15.—SPoRES 


SIMILAR FUNGI ON ROSACEOUS TWIGS 


This fungus evidently belongs to the form genus Cytospora Ehrenb. 
(Cytispora Fries.) Several Cytosporas have been referred, on more 
or less conclusive evidence, to the ascigerous genus Valsa Fries. It 
is therefore of interest in connection with this canker to note other 
eankers that have been reported upon related hosts, due either to 
Valsa or to Cytospora. 


VALSAS ON Rosaceous Hosts 


There are more than 225 species of the genus Valsa proper noted 
by Saceardo.8 Lindau,® with a broader conception of the genus, says 
there are about 400 species. The following list, tho not entirely com- 
plete, at least contains the names of the most important of these, from 
the viewpoint of pathology, that occur on Rosaceous hosts. The 
synonomy and conidial relations, when stated, are as given in the arti- 
ele cited.? 


1. Valsa ambiens Fries (1:565) (2:120) conidia—Cytispora carphosperma Fries 
(2:120) (5)=—Cytispora leucosperma Fries (25:826)—C. ambiens Fr. 
(7:2,729). On apples in Europe (8:1,131) (11:278). On most deciduous 
trees (5) 

2. Valsa acclinis Fr. on Pyrus (8:1,130) 

3. Valsa amphibola Sace. on Pyrus (8:22,354) 

4. Valsa ceuthosporae Cke. on Prunus (8:1,143) 


1The first number given in parentheses refers to the Bibliography, as does also any 
number standing alone in parentheses. Numbers following indicate volume and page. 


1919] An APPLE CANKER DUE TO CYTOSPORA 373 


20. 
21. 
22. 
23. 


24. 
25. 


26. 
27. 
28. 
29. 


30. 
31. 
32. 


33. 
34, 
35. 
36. 


Valsa ceratophora Tul. (5) (8:1,108) on broad-leaved twigs in Europe 
and North America 


Valsa cerasi Feltg. on Prunus (8:17,563) 


Valsa cincta Fries (10) (8:1,143) (5) on Prunus in Sweden, London, Ger- 
many, and France—Cytospora rubescens Fr. (33) 


Valsa coenobitica (de Not) Ces. and de Not (5) on broad-leaved trees in 
Germany and Italy 


Valsa clypeata Fuck. on Rubus (5) (8) 

Valsa coronata (Hoffm.) Fr. on Crataegus (8)—Cytospora 

Valsa crataegi Allesch. on Crataegus in Europe (5) 

Valsa cydoniae on Cydonia vulgaris in Portugal (5) 

Valsa excipienda (5) Karst. on Sorbus (8:1,139) Finland and Lapland 

Valsa excorians C. and E. on Pyrus (8) 

Valsa flavovirescens (Hoffm.) Nitz. (5) on various broad-leaved trees in 
Europe : 
Valsa hoffmanni Nitz. on Crataegus (8:1,118)—Cytospora. On peach, plum, 

and almond (29:485). On apricot 

Valsa lauro-cerasi Tul.—Cytospora lauro-cerasi on Prunus (8) 

Valsa lata (Pers.) Nitz. (5) on various broad-leaved trees in Europe 

Valsa leucostoma (Pers.) Fries (8:1,139) (10) (22) (2:120) (5) (28) 
(27:515) (4)=V. personii Nitz. (5)—Cytospora rubescens Fr. (5) (14) 
(33) (11:278)=C. leucostoma (10) (6:180). On Prunus in Europe 
(34) and North America (8) (4:264). On pome and stone fruits in 
Europe, Australia, and America (11:278). On peach, plum, and almond 
(29). On peach, plum, apricot, and cherry (14). On cherry in Amer- 
ica (9:184). On peach (4:264) (15). On cherry (10) 

Valsa leucostoma Fr. var. cincta Rolfs, common on stone and pome fruits 
everywhere (9:180). On peach (9:300) 

Valsa leucostoma Fr, var. rubescens Rolfs. On apricot and almond 
(9:157). On plum: (9:360) : 

Valsa massariana de Not on Sorbus (8:1,138)—Cytospora 

Valsa macrostoma Rehm. on Prunus (8:1,145) 

Valsa maheleb C, and E. (8:1,137) on Prunus 

Valsa maura (Fr.) Nitz. (5) on wood of Prunus spinosa in Sweden and 
Germany 

Valsa microspora (Crouan) Sace, on Crataegus (8) 

Valsa microstoma (P.) Fr.=(Cytospora microstoma) on Prunus (3) (7) 
(8:8,111) 

Valsa monadelpha Fr. on Prunus (8:1,128) 

Valsa opulifolia Pk. on Spirea (8:9,449) 

Valsa prunicola Pk. on Prunus (8:9,452) 

Valsa prunastri (Pers.) Fr. on Prunus in Europe and North America (5) 
(2:111). On plum, apricot, and pear (4:264) (13:218) (6) pyenidia= 
Cytospora rubescens (2:111) (12:196). Lindau (4:264) says the con- 
nection is doubtful. On apple, plum, ete. in England (11:278). On 
apricot, peach, and plum (26:77) 

Valsa rhodophila B. and Br. on Rosa (8:1,136) 

Valsa rubi Fuck. on Rubus (8:1,109) 

Valsa sorbi (All. and Schw.) Fries (5) on Sorbus in Europe=Cytospora 
rubescens (12:196) 

Valsa siberica Thiim. on Cotoneaster (8) 

Valsa sorbicola Nitz. on Sorbus (8:1,124) 

Valsa sepincola Fuck. on Rosa and Rubus (8:1,134) 

Valsa tumidula Cke. and Pk. (5) on Crataegus and Platanus 


374 BULLETIN No. 217 [May, 


In the accompanying tabulation are given the Cytosporas recorded 
as such on Rosaceous hosts; also the Cytospora-like conidial forms of 
various Valsas on Rosaceae. 


CYTOSPORAS AND CYTOSPORA-LIKE FORMS ON ROSACEAE 
Arranged in order of minimum spore length (1) 


Saccardo Spore 
No. Name Vol. Page|LengthxBreadth| Shape | Locules 
1)C. cerasicola Sace. ........ 3 255 3X1 Curved Many 
2|C. dendritica Berl. and Vogl.| 10 244) 3-4X.5 Allantoid | Many 
3|C.asterophora Sace. ...... 3 254 3.5-4X1 Allantoid | 4-5 
AV. japonica . ...c..ceees bs] “oe: oe al Oeeebaet sae, Obe sc, pa Spe ese e 
5|C. rubescens Fr. ......... 3 253 7 Allantoid |........ 
6|V.ceratophora Tul. ....... 1 108 4X1 - | Allantoid |Many 
7 |C. candida Speg. .......... 22 956 '46X1 Curved |...csee 4 
8|C. microstoma var. amelan- 
chéeris Cke. 2.53 eases 10 244 ay Aa CSE einirnner ys . 
9|C. leucostoma (Pers.) Fr...| 3 254 a ke TN EPS a sepilsc eae 
10|C. capitata Sace. and Schl...| 3 254 5-6 Oblong- 
botuliform|Sinuous 
11|V. hoffmanni Nitz. ........ 1 118 5-6X1 Allantoid |,....... 
12|V.microstoma (P.) Fr.....| 1 111 5-6X1.4 | Allantoid |Many 
13 |C. rosarum Grev. ......... 8 253 5-6X1.5 | Allantoid |Many 
14|C. carphosperma Fr. ...... 3 274 5-6.5 Allantoid |,....... 
15|V.rhodophila Berk. and Br.| 1 136 5-7X1 Allantoid |Many 
16|V.excipienda Karst. ...... 1 189 as ee PETE . | Many 
17 |C. niphostoma Sace. ....... 11 509 5-8X1-1.5|Allantoid |Many 
18|C. farinosa Feltg, ........ 18 297 §.5-7X1.5-2) 0. oes Few 
19|C. cydoniae Schl. ......... “22. 955 Ci} She Pits Many 
20|V.coronata (Hoffm.) Fr...| 1 110]. 6X1 Allantoid |........ 
21'C. clypeata Sace. ......... 3 252 6x1 Allantoid |Many 
22 |C. ambiens Sace. .......... 3 268 6X1 Botuliform |........ 
23... sepincola: Fol: occ ci. 4.0070% 1 134 6X1.5 |Curved Many 
24|V. massarriana de Not. ....| 1 138 6-7 X1 Allantoid |........ 
25|C. microspora (Cda.) Rabh.| 3 253 6-7 X1-1.3).......... Many 
26|C. microstoma var. cotoneas- 
WG cA whan as anen meeak 10 244 G-2 X25. View View enw sb beeen 
27 |C. lauro-cerast Fuck. var. 
ramulorum Sace. ..... 3 276 6-8 X1 Botuliform |........ 
28 |C. cincta Sace. ........... 3 254 6-9 X1.5-2|Curved Few- 
many 
29|C. cydoniae B. and K. ..... 18 297 6-9 x2 Allantoid |Many 
30 | C. anceps’ Saces: 005 esc 8 255 6-10X1 Allantoid |1-—few 
31|C. folticola Lib. .......... 3 275 7X1 Botuliform |........ 
32 |C. mespilt Sace. .......... 11 509 7X2 Allantoid |Many 
33 |C. prunorum 8. and 8. ..... 18 297 7-8X1.5-2|Allantoid |Many 
34|C. crataegicola P. Brun. ...| 14 915 7-8X3 Straight |........ 
35 |C. leucosticta Ell, and Bart.| 14 916 7-10X1.5 (Curved /|Many 
36/|C. cincta Sace. var. amyg- 
dalina Karst, ........ 10 245 7-102 Curved Many 
37 |C. macularis Sace. and Schl.| 3 256 8x3 Allantoid !\......- 


1919] AN APPLE CANKER DUE TO CYTOSPORA 375 
Saccardo Spore 

No Name Vol. Page| Lengthx Breadth Shape | Locules 
38 |C. oxycanthaevar.monogynae| 14 915 8-9 X2-2.5 Botuliform | 10-12 
39 |C. cotoneastri Thm. ....... 3 256 O- TOMES hos oc Speavtidtigannas 
40|C. phyllogena P. and S.....| 3 275 10-12 X2.5-3).......... Many 
41|C. eutypelloides Sace. ...... 22 956 11-14X1.5-2)Allantoid {20-30 
42|C. prum Ell. and Dear. ....| 11 509 12-16 X2.5-3|Fusoid 1-2 
43 |C. selenospora Oud. ....... 16 . 903 ES Bic Oy tains lees sia che ia eeovs am 
44|C.acharti Sace. .......... Pa OG. ia) Inca gwicisve's ooeee (Curved 1 
45 |C. radophila Sace, ........ Reem tll eee chase cow vine ooliolalt ca vies wraliaelsieeaes 
46 |C. rhodocarpa Sace. ....... A PRE Ue ot nO cen chai ale\Sieibon ines - kere ; Many 
47 |C.rubé Schw. .......0c00. Ea TRUS ET Tec shape CLs aia’e widcnllic bis cera eh wce: aor sremscerete 
48 |C. piricola West. .......... Date eR OLad atic ad thalee asl etecaecaifaiand'c's:s malsleie Seiaie wie 
49 |C. oxycanthae Rab. ....... : ae. ee ee Sierpisiolieiere acne tere Many 
50 |C. persicae Sch. .......... Bair aM pate wis cin, ois 010160 | sieves Cass Falun teeee 
51|C. personata Fr. ........-- Bx DR Fr eviaeesaadses Curved Many 
53 1C. lewcpapermag. (Pork.) Brit = SB ye a coi e's cine oto 0]'s 50 se cveeee seeseae 
53 |C. flavo-virens Sacec. ....... Dae BOOM We Ne es cua aiaeuesess Carved. hoa 
54|C. floccosa Wallr. ......... Big COBIAN occ! f alate's aieleine litera 8'0;s-0) sielefi ace oteseioee 
55|C. globifera Fr, ........¢. Died ASMP ne Bake otis ic, oie etelereiftetara’s aid ore eral Lote) tpitlers 
56|C. henderson Berk. and 

LON. oo oic Fa eaalre'ste HS fey 457 ta FI ee ert Carved eSscivees 
57|C.leucophthalma B. & C. ..| 3 255 Small Carved “rls ws este 


The questions of the identity of the various species of fungi 
similar to this, and of their parasitism, are interesting and are worthy 
of consideration. Obviously final classification must rest on rather 
complete knowledge of both the ascigerous and the conidial stage 
and of the biologic or host relationships. As to all of these much 
uncertainty at present exists. The genus Valsa as treated by Lindau‘ 
contains the subgenera Eutypa, Endoxyla, Cryptosphaeria, Crypto- 
valsa, Cryptosphaerella, Endoxylina, Leucostoma, Eutypella, Euvalsa, 
and Valsella, chiefly distinguished from each other in stromatiec char- 
acters. Saccardo treats of these subgenera as genera. Many sugges- 
tions as to the ascigerous connection of conidial forms have been made, 
often based merely on the association of the two forms on the same 
twig. Many of these claims are conflicting, assigning several conidial 
species to the same Valsa, e. g., at least three Cytosporas are given as 
the conidial form of V. ambiens ; or several Valsas to the same conidial 
form, e. g., C. rubescens is by various writers connected with at least 
four separate Valsas. As to the parasitism of these forms there has 
also been much discussion and divergence of opinion. Many species, 
probably a large majority of them, are purely saprophytic, growing 
only on dead twigs; some follow closely on frost injury or injury 
from other causes, or may be classed as wound parasites. Con- 
cerning the particular question of parasitism of Valsa on drupes: 
Goethe,°° Labonte,*® Sorauer,*® 49 Raschen,47 and Zapfe,37 held the 


376 BuLLETIN No. 217— [May, 


fungus to be secondary, while Frank,*®: 44 Aderhold,!® Stewart e¢ al.,1§ 
Rolfs,14 15.16 and later several others,*: 2° 52 have held that it was 
the cause of the disease, a view that is now definitely established. 

The most comprehensive articles bearing on Cytospora and Valsa 
on drupes are by Aderhold 1° and Rolfs.1® Aderhold referred the 
form on drupes to Valsa leucostoma, and by extensive cultural and in- 
oculation studies demonstrated. its parasitism. 

Rolfs studied Valsa on peach, plum, apricot, and cherry, and 
showed that the forms are interinoculable; but on the basis chiefly of 
slight variations in spore measurements, tho to some extent on vari- 
ations in growth on media, he distinguished two varieties, V. leu- 
costoma var. cincta on cherry and peach, and V. leucostoma var. 
rubescens on apricot and plum, a varietal distinction that has been 
recognized in at least one textbook. That such a varietal segregation 
should exist is somewhat surprising, especially when the biologic re- 
lations claimed are considered, and the question naturally arises as 
to the validity, for taxonomic purposes, of the characters selected. 

While the literature regarding Valsa and Cytospora on drupes is 
extensive there are but few references to either as causes of disease 
on cultivated pomes. 

Aderhold’® made inoculations upon apple, but makes no reference 
in later publications to its natural occurrence upon that host, tho 
in 190045 he recorded it as the cause of cankers on pear in Proskau. 

Von der Byl,®? also Evans,5* noted Cytospora leucostoma as the 
cause of die-back of apple trees in South Africa; Darnell-Smith and 
MacKinnon?’ report Valsa and Cytospora on apple in New South 
Wales; Nicholls®+ reports death of apple trees in Tasmania associated 
with Valsa prunastri and Valsa ambiens; and Ideta?* in his textbook 
gives Valsa mali as the cause of canker on apple twigs. The illustra- 
tions given by Darnell-Smith agree closely with the canker under 
discussion. 

Cockayne*> mentions what is probably a Valsa on apples, pears, 
and other trees in New Zealand, but with inconclusive evidence as to 
parasitism and as to the species of fungus involved. 

To place clearly before the reader the difficulties of classification 
and the necessity of taxonomic revision of these fungi the preceding 
tables and lists are presented. Truly Aderhold was justified in con- 
eluding that from the conidial forms alone it is impossible to make a 
specific determination. 

Tho the fungus here discussed agrees well with the Cytospora of 
Valsa leucostoma, it is best to defer final judgment as to its specific 
name. It is to be noted that many similar fungi described on other 
hosts may in fact also grow on Rosaceae; also that Cytosporoid fungi 
belonging to genera of the Valsaceae other than Valsa may cause 
cankers on these hosts. 


1919] AN APPLE CANKER DUE TO CYTOSPORA 377 


10. 


MM. 
12. 
13. 


14. 
15. 


16. 


af 
18. 
19. 
20. 
21. 


22. 


23. 


BIBLIOGRAPHY 


MASSEE, GEORGE. Diseases of Cultivated Plants and Trees. 1910. 
CooxE, M. C. Fungoid Pests of Cultivated Plants. 1906. 


ALLESCHER in Rabenhorst, L. Kryptogamen Flora von Deutschland 1. Pt. 
6. 1901. 


Linpav in Sorauer, P. Handbuch der Pflanzenkrankheiten, 2. 1908. 
Linpav in Engler and Prantl. Die Natiirlichen Pflanzenfamilien, 1. Abt. 1. 


Rant, A. Die gummosis der Amygdalaceae. Diss. Amsterdam, 1906. In 
Ztschr. Pflanzenkrank., 17, 179. 1907. 


Winter, G. Die Pilze in Rabenhorst’s Kryptogamen Flora von Deutsch- 
land, ete. 

Saccarpo, P. A. Sylloge Fungorum Omnium Hucusque Cognitorum. 

HEsueER, L. R., AND WHETZEL, H. H. Manual of Fruit Diseases. 1917. 

ADERHOLD, R. Ueber das Kirschbaumsterben am Rhein, seine Ursachen und 
seine Behandlung. Arb.a.d. Biol. Abt. fiir Land und Forstw. Kais. 
Gsndhtsamt., 3, 309, 563. 1903. An extensive discussion of the morph- 
ology, taxonomy, and pathogenicity of the fungus, with studies of pure 
cultures. See also review in Zeit. Pfk., 15, 339. 

Stevens, F. L. The Fungi Which Cause Plant Disease. 1913. 

FucKkeL, L. Symbolae Mycologicae, 196. 1869. 

DUKE OF BEDFORD AND PICKERING, 8S. U. Observations on a Disease of Plum 
Trees. Report on the working and results of the Woburn Experimental 
Fruit Farm, Report II, 218, London, 1900; also review in Zeit. Pfk., 
12, 177. Reports Eutypella prunastri Sace. on plum and almond. 

Routrs, F. M. Die Back of Peach Trees. Science, 26, 87, July, 1907. Cyto- 
spora rubescens followed by its ascigerous stage Valsa leucostoma is 
given as the cause of the disease on peach and plum. 

A Disease of Neglected Peach Trees. Mo. St. Bd. Hort., Rpt. 2, 
278-83. 1908. Due to Cytospora (Valsa leucostoma), which he thinks the 
same as that reported by Stewart et al.’ 

Winter Killing of Twigs; Cankers and Sunscald of Peach Trees. 
Mo. St. Fruit Exp. Sta. Bul. 17, 1-101. 1910. An extensive account 
of the morphology, pure cultures, and inoculations. Two varieties of 
Valsa leucostoma are erected, var. cincta on cherry sa peach, var. 
rubescens on apricot and plum. 

Waters, R. Jour. Agr. N. Zealand, 14, 190-96. 1917. Netéa presence of 
Valsa ambiens (?) and Valsa auerswaldia as saprophytes or facultative 
parasites on apple and other fruit trees. 

Srewart, F. C., Routrs, F. M., anp Hatt, F. H. A Fruit Disease Survey 
of Western New York. N. Y. (Geneva) Agr. Exp. Sta. Bul. 191, 304, 318, 
323. 1900. Cytospora sp. on apricot, peach, and plum. 

McALPINE, D. Fungus Diseases of Stone Fruit Trees in Australia and 
their Treatment. Melbourne, 1902. 

WorMALD, H. The Cytospora Disease of the Cherry. Jour. Southeast Agr. 
Col., Wye, Kent., No. 12, 367-80, pl. VII-XXII. 1912. Description 
of canker with plates; studies of morphology, pure cultures, and inocu- 
lations. Attributed to Cytospora leucostoma—Valsa leucostoma. 

LtstHer, Gustav. Untersuchungen iiber die Ursache des Rheinischen Kirsch- 
baumsterbens. Ber. d. Konig]. Lehranst. fiir Wein Obst u. Gartenbau, 
Geisenheim a. Rh. (1907) 307. 1908. 

Ewert. Ist das Rheinische Kirschensterben auf eine Pilzekrankheit zuriick- 
zufiihren, Proskau. Obstbau Ztg., 13, 2-8. 1908. 

Ipeta, A. Handbook of Plant Diseases of Japan, 295. 1909. Gives Valsa 
mali Miz. and Yam. on apple. 


378 


50. 
51. 


BULLETIN No. 217 [May, 


LAPINE, FRANK N. Zum Krebs der Apfelbaiume Landw. Jahrb. 21, 937-49. 

CooxE, M. C. Handbook of British Fungi. 1871. 

Hartig, R. Lehrbuch der Pflanzenkrankheiten. 1900. 

KIRCHNER, O, Die Krankheiten und Beschaidigungen unserer Landwirt- 
schaftlichen Kulturpflanzen. 1906. 

Frigs, E. Systema Mycologicum, 2, 387, 1823, 

Eu.is, J. B., AND EVERHARDT, B. M. North American Pyrenomycetes. 1892. 

GOETHE, R. Das Absterben der Kirschenbaéume in den Kreisen St. Goar, 
St. Goarshausen und Unterlahn. Deut. Landw. Presse, 26,999, 1111-12. 
1899. The Cytospora is regarded as secondary following frost injury. 

ScHROETER, in F, Cohn’s Kryptogamen-Flora von Schlesien, 3,I1,405. 1908. 

RUHLAND, W. Untersuchungen zu einer Morphologie der Stromabildenden 
Sphaeriales auf entwicklungsgeschichtlicher Grundlage. Hedwigia, 39,1. 
1900. 

NITSCHKE, TH. Pyrenomycetes germanici, 223,228. Breslau, 1867. 

Ltstrer, G. Beabachtungen iiber das Rheinische Kirschbaumsterben, 1906. 
Ber. d. Kénigl: Lehranst. fiir Wein Obst u. Gartenbau, Geisenheim a. 
Rh., 1905. Review in Zeit. Pfk., 16, 324. 

CockaYyNnE, A. H. Jour. Agr. N, Zealand, 11,504. 1915. A die-back of 
apples, pears, and other fruit trees is noted. A Valsa may be the cause, 
but the evidence is incomplete. 

WEHMER. Zum Kirschbaumsterben am Rhein. Deut. Landw. Presse, 26,96, 
1080. 1899. Cites presence of Valsa leucostoma. 

ZAPFE. Kirschenzucht und Kirschbaumkrankheit in Camp a. Rh. Prakt. 
Rathgeber Obst u. Gartenbau, 14,473.. 1899. 

DaRNELL-SMiTH, G. P., AND MACKINNON, E. Fungus and Other Diseases of 
the Apple and Pear. Dept. Agr. New South Wales, Farmers’ Bul. 99, 18. 
1915. Reports Cytospora and Valsa on apple. 

WALTON, R. C., AND Bascock, D.C. Abst. Phytopath, 6,112. 1916. 

FRANK. Das Kirschbaumsterben am Rhein. Deut. Landw. Presse, 26,249. 
1899. ; 

Gelungene. Infektionsversuche mit dem Pilze des Rheinischen 
Kirschbaumsterbens. Deut. Landw. Presse, 27,1024. 1900. True para- 
sitism of the fungus was proved by inoculations. 

Rours, F. M. Fruit Tree Diseases and Fungicides. Mo. St. Fruit Exp. Sta. 
Bul. 16, 15-16. 1907. Attributes die-back to Valsa leucostoma= 
Cytospora rubescens, 

PERSOON, C. H. Synopsis Methodica Fungorum, 39. 1801. 

ADERHOLD, R. Unserer Obstbaume Hausarzt, Proskau. Obstbau Ztg., 37. 
*1899. : 

Arbeiten der botanischen Abteilung der Versuchstation des 
Kgl. Pomologischen Instituts zu Proskau. Centbl. Bact., II, 6,620. 
1900. Cytospora rubescens noted on pear. 

LaBontE. Die Krankheit der Kirschbiume am Rhein und ihre verschiedenen 
Ursachen. Mitt. iiber Obst u. Gartenbau, 102. 1900. 

RASCHEN. Kirschbaumsterben und Kalkdiingung. Deut. Landw. Presse, 
27,1,7. 1900. No mention is made of parasitic fungi. 

SorAvER, P. Das Kirschbaumsterben am Rhein. Deut. Landw. Presse, 27,18, 
201. 1900. Holds the fungi to be secondary. 

Das massenhafte Absterben der Siisskirschen am Rhein. Naturw. 
Wehnsehr., 15,133. 1900. 

TASCHENBERG, O. Schutz der Obstbaiume gegen feindliche Tiere, III, 108. 

HEALD, F. D. Report on Fungous Diseases. Tex. Dept. Agr. Bul. 22,158. 
1911. 


1919] AN APPLE CANKER DUE TO CYTOSPORA 379 


52. 


53. 


54. 


55. 


56. 


57. 


Hemi, T. On a New Canker Disease of Prunus yeodoensis, P. mume ana 
Other Species Caused by Valsa japonica n, sp. Jour. Col. Agr. Tohoku 
Imp. Univ., 7,257. 1916. These fungi cause disease and gummosis. 

Von vDER ByL, P. A. Die Back of Apple Trees Caused by Cytospora 
Leucostoma, So. African Jour. Sci., 12,545, 1916. Reported as serious 
on apples in many localities; also on drupes. 

NicHoutis, H. M. Agr. and Stock Dept. Tasmania, Rpt. 1916-18. Valsa 
prunastri and Valsa ambiens are reported on dying apple trees. 

StérMeEeR, K. Obstbaumsterben und Kartoffelblattrollkrankheit. Jahresb. 
Ang. Bot., 7,119: 1909. Discusses Valsa leucostoma as the cause 
of death of cherry trees, and Cytospora piricola of death of apple trees. 

Evans, I. B. P. Union So. Africa, Dept. Agr. Rpt. 1912-13, 169. Cytospora 
leucostoma is reported as causing death of apple trees. 

SPRENGER. Influences Affecting Cherry Culture. Cultura, 27,325. 1915. 


fit uy 


